Rafter-gage.



No. 821,168. PATENTED MAY 22, 1906.

V. A. JOHNDRO. RAFTER GAGE.

APPLICATION FILED JULY 21 1905.

J 6' 71 5 i f I/WE/VTOR dzidfi 777081715X I STATES PATENT OFFICE.

RAFTER-GAGE.

Specification of Letters Patent.

Patented May 22, 1906.

Application filed July 21,1905. Serial No. 270,677.

To all whom it may concern.-

Be it known that I, Vro'ron A. J OHNDRO, a citizen of the Dominion of Canada, residing at New Westminster, in the Province of British Columbia, Canada, have invented a new and useful Improvement in Rafter-Gages, of which the following is a specification.

My invention relates to an improved means for determining the length of rafters whether for gable, hip, or octagon roofs and the seat, plumb, and side cuts of their ends. It is designed as a bevel-square of particular construction having means for setting the bevelblade to the specific angles required, the stock of which may be applied to an ordinary carpenters square, and the half-span and pitch of the roof being determined the length of the desired rafter may be read off from the blade of the bevel, square, or gage which is the subject of this application and the bevel of end cuts ascertained. The determination of such particulars, although theycan be ascertained from an ordinary steel square such as is used by carpenters, frequently requires a familiarity with the use of the square which carpenters do not always possess to a sufficient extent to avoid, error, and my gage is intended to facilitate such determination.

The articular construction of the gage and its ap ication to determine these particulars is ful y described inthe following specification, and illustrated in the drawings which accompany it, in which Figure 1 is a plan of the square; Fig. 2, an end elevation; Fig. 3, a plan showing the application of the gage to a carpenters square in determination of the desired particulars. Fig. 4 is a plan view of the arc-segment.

In the drawings, 1) represents the stock, within a recess of which is mounted a blade 0 in such a manner that the zero end of the graduated portion of the blade is always coincident with the face edge of the stock. As to attain this coincidence it is impracticable to mount the blade upon a pivot-pin, it is mounted upon two concentric arcs, d and e, (1 being of small radius and cut in the body of the blade from a center at the zero end of its graduation and having a short segment f secured in the body of the stock, so as to slidably fit the are d. The other arc-segment e is of larger radius and of sufficient width to afford space for the various graduations required, the use of which will be ex lained later. It is secured to the face of the lade c and passes through the body of the stock,

which is provided with an outer plate g, which although secured to the stock along its length is free to be tightened upon the arcsegment 6 by a butterfly-nut h, threaded on a screw or stud i, secured .in the body of the stock. The blade 0 by means of these concentric arc-bearings is enabled to be moved to and secured at anydesired angle, while the zero end of its graduated edge is at all times coincident with the face edge of the stock I).

The description thus far constitutes the mechanical construction of the gage.

The outer edge of the blade 0 is graduated in any desired unit which may be found convenient. As illustrated, it is designed for builders, and the edge of the blade is divided into inches, which are subdivided into twelfths, so that its graduations may represent feet and inches. The inneredge of the segmental are e is divided into any desired unit of angular measurement, such as degrees, and outside of this the surface of the segment is divided by a series of concentric lines into spaces which at the end where the arc is secured to the blade are marked with numbers which represent the various pitches of roof in terms of the rise for one. foot run, as (6,77 8}!) (9,7) ((10, (12, 7 ((18,) 24. In the spaces indicated by these figures a series of cross-lines is inscribed indicating the angle of roof-slope required for each pitch for common C, octagon O, or hip H rafters, and if the blade of the bevel-gage is set to any one of these oross-lines and the stock of the gage placed against the tongue of a carpenters square with the pivot-center of the bevel to the dimension representing to scale the half-span of the roof the length of rafter required may be read to the same scale from the blade C, where it intersects the outer edge of the blade of the carpenters square.

In addition to'the letters 0, O, and H on these several cross-lines they are marked, respectively, withthe numbers 12 13, and 17, and these numbers,with those at the end of the spaces, indicating the rise of the roofpitch, will indicate the number on blade and tongue of the carpenters square required to give the seat and plumb cuts for the ends of the rafter. For example, assuming that a rafter common, octagon, or hip is required for a roof having a rise of eight inches to a foot, the blade 0 of the bevel-gage will be set to the cross-line C, O, or H, as the case may 0 With the edges of the tongue and blade of "sive movement of the zero-point the amount be, on the space 8 of the arc-segment e, and I the stock I), being set a 'ainst the ton ue of a carpenterssqu'are, will give on the "lade c of the gage in the manner previously described the length of rafter required, and the seats and plumb cuts of the rafter ends will be given'bythe numbers 12/8, 13/8,'or 17/8, which Will be used in the customary manner from the tongue and blade of a car penters square.

In-all cases Where a side out is re ui'red it is obtained from the intersection of t e blade the carpenters square,'cu'tting always on the blade'edge and ii 'inobtai-ning this bevel the zero-'point'of the blade is moved to 12'on the tongue of thecarpenters square the cut Will be expressed in terms of 12, Which Will be easier to remember.

The bevel-gage may also be used to determine the shortening of the jack rafter's ata hip in the following manner: Set the bevel gage to the hip 'mark for the pitch of roof required and apply the Zero-point of the blade 0 to the half span of the roof in feet and inches on the ton ue of the carp'en'ters square, space 'oif the number of inches the centers of t e rafters are apart ,and move the z'cr'o poi-nt of the bevel that amount to the left, when the point of intersection of the edge of the bevelblade 0 with the blade -of the c'arpenters square Will'give onthe blade of the"carp'enters square the length of the first jack-rafter. The others can be obtained either by succesof pitch to the left or having ascertained the amount of shortening by deducting it, as required. The side out bevel will be determined on tongue and blade of the carp-enters square in-the manner previously described.-

To enable th'e'ishorteiiing of the jack-rafters to be ascertained when the tongue of the carpenters square does not happen to be divided into inches and twelfths,' I provide toward the mid-length of the contact edge 1 of the stock b'a short scale so divided that the rafter-pitch movementto the left may be made. k v

There are several other determinations frequently required by carpenters which the use of this bevel-gage simplifies; but as the description of them is not material to this application they need not be here ex lained.

Having noW particularly describe my inventionand the manner of its application, I herebydelare that What I claim'asneyv, and desire to be protected in by Letters Patent, is

1. In a bevel-gage for the purpose specifled; the combination with a stock, of a blade member mounted on concentric arcs the center of which is coincident with the edge of the stock, one of Which-arcs toward the axis of movement is cut in the blade member and has an arc-bearing in the body of the stock, the other bein mare-segme t secured to the blade and passing through the body'of the stock, desired raduat'ions' on the face of the last-'naniecl aro segment, and means forclamp'ing the stock to the are gment at any desired position of angular movement. a I

2. In a bevel-ga e for the purpose specifled, the combination Wi'th'a'stockhavi'riga recess in one edge face, of a graduated blade member fittin the recess and mounted on concentric arc bearings the "center of when is coincident with the recessed "edge of. the stock the arcfbearin'g adjacent to the" axis "of movement of: the blade beingcii't in the body of the blade and provided with a bearingsegment in the body of the stock, the other arc-segment secured to the blade member and passing through the body of the stock having means on the stock for clamping it in any desired position of angular movement, and a series of raduations the faeeo'f the l'ast name'd are segment indicating" the an;- gle's or bevel re uired for various slopes of roof-pitches', and numbered to" give the cut of bevel for the rafter ends. 7 p y In testimony whereof I h'ave signed'in name to this specification in the presence of two subscribing Witnesses.-

VIOTOR A. JO'HNDR'O. Witnesses:

Trioihiis Annxnivnnit MARTiN, ROWLAND BRITTAIN. 

